Bone audition apparatus



Feb.21,1939. KOCH I 2,148,024

BONE AUDITION APP/Rufus Filed June 29, 1933 nl I "III- Tu-l/ ATTORNEYS Patented Feb. 21, 1939 AUNITED STATES PATENT OFFICE mph Products Company,

Inc., Jamaica,

Application .rune as, 193s, serial No. 678,130 14. claims. (o1. 11s-1o?) This invention relates to audition apparatus or audiphones land has particular reference to apparatus for transmitting sound vibrations through bone as compared to transmission of gy sound through air.

It is well known that the majority of persons aiilicted with partial or entire deafness can hear well when the sound vibrations are transmitted to the inner ear, and that the reason that such persons are deaf is because their hearing organs do not adequately respond to sound vibrations transmitted through the air, 'I'his condition can be remedied by transmitting the sound vibrations through the bone structure of the head to the inner ear by contact between the head and a member which vibrates in accordance with vibrations within the audible frequency range.

'I'his principle has been utilized heretofore in apparatus for aiding the hearing of deaf persons zo in which a tympanum or reed, vibrating in accordance with audible sounds, is placed against the bony structure of the head, so that its vibrations are transmitted through the bone to the inner ear. These instruments are not satisfactory, largely because the vibration of the tympanum or reed is suppressed or otherwise interfered with by the contact between it and the head of the user. In other words, the tympanum or .reed which reproduces the sounds is not free to vibrate in conformity to the'sound transmitted to it and distortion results, which is frequently so violent that the user hears only confused noises and accordingly his hearing ls not aided by the instrument. Furthermore, it is, even under the -most favorable Operating conditions, extremely diflicult to maintain the uni form, light contact of the tympanum or reed on the head, which is essential even in imperfect bone audition.

In accordance with the present invention, a bone audition apparatus or audiphone is provided which is free of the Objections of the former apparatus of that type, in that the degree of pressure with which the tympanum or reed er1- gages the head does not materially affect the response or sensitivity of the instrument', the performance of which remains constant at all times, even under the most severe voperating conditions.

The apparatus of this invention operates on an inertia principle, that is to say, the magnetvupon `which the voice `or speech coil is preferably mounted, is carried by the reed and is massive so that it has a high relative inertia with respect to the reed, which bears a relatively'xed relation to the magnet, subject, of course, to the variations caused by the vibrations thereof in response A to the fluctuations in the speech current traversing the coil. With this construction, the reed vibrates relatively to the magnet, which, in effect,

remains stationary due to its inertia, so that where the apparatus is supported by the reed the latter may be placed against the head of thev user with any degree of pressure without impairing the freedom of vibration of the reed.

It will be seen that the new apparatus of this invention remains sensitive and. is uniform in operation during all conditions of use, may be used successfully by unskilled persons, and may be manufactured in large quantities with uniform Operating results. The apparatus may also be employed without substantial change in connection with the usual sound detecting and amplifying-systems common in audition apparatus.

For better understanding of the invention, reference may be had to the accompanying drawing, in which,

Figure 1 is an enlarged longitudinal section through the bone audition receiver of this invention, as seen along the line I--I of Figure 2;

Figure 2 is a transverse section of the receiver as seen along the line 2-2 of Figure 1;

Figures 3 and 4 illustrate two ways of holding the new receiver when it is in use; and

Figures 5,' 6 and 7 are longitudinal sections through three modified forms of the receiver of this invention. A

Referring to Figures 1 and 2 of these drawings, numeral I0 designates the casing of the in strument A of this invention. It is formed of substantially non-resonant material, such as hard rubber, a synthetic resin, or the like, and includes a cap plate II secured in position by screws I2. A pair of terminal plates I3 are inlaid flush with Athe inner surface of cap plate Il and are tted at their inner ends with terminals I4 and at their outer ends with contacts I5.

Adapted to engage each of contacts I5 is a contact spring I6 seated in a corresponding recess 'in casing I0 and engaging at its opposite end a plug I'I having a pin I8 projecting into a lateral passage I9 in the casing. The pins I8 are adapted to make electrical contact with the connectors 20 of cord 2| inserted in passages I9 for the purpose of connecting the terminal plates I3 to a` conventional audition' circuit including microphone 22, battery 23, as illustrated graphically in Figure 3, together with suitable amplifiers, rheostats, and the like, not shown.

Rigidly secured to the inner surface of @cap plate I I by means of screws 24 is a reed 25o! iron,

` steel, their alloys, or other suitable magnetically permeable metal. One end 26 of the reed 25 is extended upwardly into the casing I at substantially right angles to the reed 25, so that the reed is L-shaped. The upstanding end 26 of the reed 25 carries at its free end a massive permanent magnet 21, which is connected thereto by a plurality of screws 28, or the like. The mass of the permanent magnet 21 compared to the mass of the reed 25 is such that the magnet 21 has a high relative inertia, the function of which will be described later.

Rigidly secured on the free end of the permanent magnet 21 by means of screws 29, or the like, is the pole piece 3U, the free end of which cooperates with the corresponding surface of reed 25 to form a narrow air gap which is preferably between twoand three-thousandths oi.' an inch wide. Sultably secured on pole piece 30 is the speech coil 3|, the terminals of which are connected by light filamentary conductors 32 to the terminals I4 of the terminal plates I3.

While the form of the invention illustrated in Figures. 1 and 2 is preferred, several modifications thereof may be used with equal facility and comprise different arrangements of the reed, permanent magnet and speech coil. For example, in Figure the reed 25 is made perfectly flat, while the permanent magnet 21 is secured to the end of and is arched over the reed 25 in the manner illustrated, carrying the speech coil 3|' in the same way, while the electrical connections and other details are the same as those illustrated in Figure 1.

In the modification illustrated in Figure 6 the reed 25 is also perfectly flat while an L-shaped permanent magnet 21 is secured to the end thereof and carries not only the speech coil 3| and the pole piece but also a contact block 33 of insulating material to which are connected the speech coil terminals 32 and the corresponding terminals of the speech cord 2|, not shown.

In the arrangement of Figure 7 the reed 25 is perfectly flat, while the U-shaped permanent magnet 21" carries at its center portion the speech coil 3I, other details being the same as those described inconnection with Figure 1.

In order to hold the instrument just described flexibly and without restraint, several forms of holders are provided, one of which is illustrated in Figure 3. This holder comprises a handle 34 having a flexible metal stem '35, the upper end of which carries the fork 36, which spans the casing I0 of the instrument and is fitted with pins 31 at the free ends of the tines thereof, these pins being pivotally inserted in corresponding recesses in the sides of the casing IIJ at points preferably adjacent the air gap of the instrument, as is illustrated in Figures 1 and 3.

With this arrangement, the user, holding the handle 34 in his hand, places the plate I I against the bony structure of his head, preferably on the upper `law bone Ain front of the ear, on the mastoid bone behind the ear, or against some other convenient point on the bony structure of the head, preferably, however, adjacent the ear, although it is to be understood that if the vibrations received by the instrument are sufficiently amplified they may be transmitted from other parts of the body, such as the shin bone, through the bone structure of the body to the inner ear.

Another form of holder is illustrated in Figure 4 and comprises a resilient metal band 38 fitted with a fork 36', on which is pivotally mounted the instrument A in the manner described. The

band 38 is placed around the head of the user and firmly holds the vinstrument A against the head in the manner described.

In operation, the face plate II on which the reed 25 is rigidly mounted, is placed against the bony structure ofthe head of the user in the manner described. The audible sounds picked l up by the microphone 22 and suitably amplified by apparatus not shown is transmitted to the speech coil 3|, which accordingly varies the flux traversing the path including the permanent magnet 21, the pole piece 3U, the air gap and the reed 25 to set up fluctuating electromagnetic forces across the air gap, causing relative movement between the pole piece 30 and the reed 25 in accordance with the well known electromagnetic phenomenon. However, due to the relative inertia of the massive permanent magnet 21 and its appurtenant parts compared to the inertia of the light reed 25, the magnetic structure 21--30-3I, in effect, remains stationary, while the light reed 25 vibrates with respect thereto about a fulcrum located substantially at the junction of the reed 25 and its extension 26. The vibration of the reed 25 is accordingly transmitted through the bone which the face plate I I engages to the inner ear and the user hears the sounds picked up by the microphone 22.

Owing to the fact that the supported reed carries the magnet structure and vibrates relatively to the massive magnet structure, due to the high relative inertia of the latter, the degree of pressure with which the reed is applied to the vibration-transmitting surface, such as the head, is immaterial, the reed vibrating freely under all normal-operating conditions. In other words, the relation between the reed and the magnet structure, i. e., the air gap, reniains fixed subject to the vibration of the reed, so that the response of the reed is uniform and unsuppressed and any bodily movement of the reed is accompanied by equal movement of the magnet structure because the latter is carried by the reed. Also, inasmuch as the casing I0 is directly attached to the reed, the entire casing vibrates with the reed as a unit on the supporting means, such as the head band 38, holder 34, or the like.

In this important operating respect the apparatus of the present invention differs from the bone audition apparatus in current use in which reed and the magnet structure, i. e., the air gap,

is varied substantially in actual practice, depending upon the degree of pressure with which the instrument is applied, so that the free vibrations of the tympanum or reed are suppressed and the instrument responds so imperfectly to the audible sounds which it is supposed to transmit that the audition is poor and frequently unintelligible to the user.

Furthermore, because it operates on the inertia principle just described, the apparatus of this invention is uniformly sensitive for all persons and'need not be as delicate as those in current use, but may be made rugged and strong so as to stand the most severe usage without breakage or impairment ofiits sensitivity.' Also, because of its structure, the instrument may be manufactured in large quantities with uniform operating results.

While certain preferred embodiments of the invention have been illustrated and described herein, it is to be understood that the invention is not 'limited thereby, but that the principles of operation thereof may be embodied in any suitable instrument within the scope of theinvention. 'For example, the new apparatus, which is essentially a telephone instrument, may be adapted to uses other than bone audition, such as for telephone purposes, simply by making appropriate changes in the casing, the mounting of the instrument, and the like, although without substantial change it may be placed againstthe ear and the sound transmitted thereby in the manneipf air audition devices.

. I claim: V-

1. In a portable audiphone; the combination of a vibratory member, electromagnetic means carried by the member and adapted to respond to varying currents substantially throughout the audible frequency range for vibrating said member, a casing supported by the member andhousing said electromagnetic means, and means pivotally connected to theopposite sides of the casing for supporting it in operative connection with pivotally connected to said member about an axislying in a plane substantially normal tothe said surface of said member and` adjacent said gap .for self-adjustably holding the said surface of said member'in-operative connection with the bone structure of the 'user at a pointsubstantially opposite said gap, whereby the said vibra-4 tions of the mass across the gapare transmitted reactively tothe member and conducted through the connected bone structure to the inner ear of` the user.

3.v In portable' bone audition apparatus, the combination oi' a vibratory member, resilient supporting means pivotally connected to opposite sides of the memberv for holding it in operative connection with the bone structure of the user, and electromagnetic means supported by the member including an elongated reed secured to the member, an-elongated magnet connected at onev end to the reed and extending. in substantially parallel spaced relation to said reed, the association of the reed and magnet aiording limited relative movement of the free end of the magnet,

a pole piece on the free end of the magnet forming a gap with the corresponding end of the reed,

said reed. magnet and pole piece providing a continuous magnetic ux path across said gap, and windings associated with said flux path and adapted when energized by voice currents to vary the flux across said gap and thus effect vibration between said reed and magnet and' consequent reactive vibration of said member, whereby the vibrations thereof are conducted through the connected bone structure to the inner ear of the user.

' 4. In a portable bone conduction audiphone,.

the combination of a vibratory member having a relatively flat contact surface, a hollow element cooperating with the member to form a hollow housing, electromagnetic means within the housing having an amature portion secured to the member and a non-rigid portion extending free of the member, a bar magnet supported by at least one end on saidnon-rigid portion and extending in substantially parallel spaced relation to said member, a pole piece depending from said magnet toward said armature portion at a point spaced from said one end of the magnet to form a narrow air gap with said armature portion, the

said. non-rigid portion affording limitedv vibra-` said magnet and said armature portforf at the gap in a direction substantially normalzto said contact surface, windings on said pole piece adapted' when energized by voice currents to vary' the ux across said ,gap and thus effect vibration between :said armature portion and magnet in said direction whereby the member is l correspondingly vibrated by reaction, and means pivotally connected to opposite sides of saidhousing labout an axis lying in a plane substantially normal to said contact surface and adjacent said gap' for self-adjustably lholding said contact surface at a point opposite ysaid gap in operative connection with the bone structure of the user for conducting the vibrations of said member therethrough'to the inner ear. i

5. In portable bone audition apparatus, the combination of a vibratory member having a contact surface, resilient supporting means piv-` otally connected to opposite sides of the member about anaxis substantially parallel to the contact surface of the-member forfself-adjustably 4holding it in operative connection with the bone structure of the user, and electromagneticmeans supportedl thereby including an elongated reed secured to the member, an elongated magnet connected at on/e end to the reed, the association of the reed and magnet affording limited `relative movement `oi the free end of `the magnet, a pole piece on the free endof the magnet forming a gap with the reed, said reed,`mag'net and pole 6. In portable bone audition apparatus, the combination of a vibratory member adapted to be operatively connected with the bone structure of `the user, electromagnetic means supported thereby including means secured to the memberhaving anarmature portion and a non-rigid portion, a bar magnet supported at one end on said .nonrigid portion and extending in substantially parallel spaced relation to said member, a pole piece depending from said magnet toward said armature portion at a point spaced from said one end of the magnet to form a narrow magnetic gap with said amature portion, the said non-rigid portion affording limited vibration between said magnet and said armature portion at the gap, windings on said pole piece adapted when ener- .gizedby voice currents to vary the flux across said vgap and thus eilect vibration between said armature portion and magnet, whereby the member is vibrated by reaction and transmits its vibrations through the bone structure to theinner ear of the user, and resilient supporting means pivotally connected to opposite sides of the member about an axis adjacent said magnetic gap for holdingrsaid member in saidoperative connection with the bone structure of the user.

'7. In a bone conduction audiphone, the combination of an elongated housing having a relatively ilat contact surface, electrical means iloatingly supported within said housing and adapted when energized Aby voice currents to vibrate relatively to said housing and thus vibrate the latter by reaction', said means including an elongated member of substantial mass compared to the mass of said housing mounted at only one end on the housing and extendingv in substantially parallel spaced relation to said surface with its opposite end free for said vibration relatively-to said housing, and means pivotally connected to opposite sides of said housing for supporting said housing withs'aid surface inoperative connection with the bone structure of the user for conducting the vibrations thereof through said bone structure to the inner ear.

8. In portable bone audition apparatus, the combination of a vibratory member adapted to be operatively connected with the bone structure of the user, and electromagnetic means supported thereby including means secured to the member having an armature portion and a nonrlgid portion, a bar magnet supported at only one end of said non-rigid portion and extending in substantially parallel spaced relation to said member, a pole piece depending from said magnet toward said armature portion at apointv spaced from said one end of the magnet to form a narrow magnetic gap with said armature portion, the said non-rigid portion aording limited vibration between said magnet and said armature portion at the gap, and windings on said vpole piece adapted when energized by voice currents to vary the flux across said gap and thus eiTect the -reed and magnet ail'ording limited relative movement of the free end of the magnet, a pole piece on the free end oi' the magnet forming a gap with the reed, said reed, magnet and pole piece providing a continuous magnetic flux path across said gap, and windings associated with said flux path and adapted when energized by voice currents to vary the ilux across said gap and thus to effect vibration between said reed and magnet and consequent reactive vibration of said member, whereby the vibrations thereof are conducted through the connected bone structure to the inner ear of the user.'

10. In portable bone audition apparatus, the combination of a vibratory member adapted to be operatively connected with the bone structure of the user, and electromagnetic means supported thereby including an elongated magnetically permeable element secured to the member,

a bar magnet mounted by one end only` on one end of the element with the free end of the magnet extending in longitudinal spaced relation to the said element, the association of the magnet and element affording a limited relative vibration of the free end of the magnet, a pole piece on the free end of the magnet forming a gap with the element, said elementi magnet and pole piece providing a continuous iiux across said gap, and windings associated with said flux path and adapted when energized by voice currents to vary the flux across said gap and eiIect vibration be- 'association of said elements affording a limited movement between them at the gap, and windings associated with at least one of said elements for varying the continuous flux longitudinally traversing said elements in response to energization by voice currents to thereby effect relative vibration between said elements. whereby the resultant reactive vibration of the member is conducted through the connected bone structure to the inner ear of the user.

12'. In portable bone audition apparatus, the combination of a vibratory member adapted to be operatively connected with the bone structure of the user, and electromagnetic means supported thereby including an elongated magnetically permeable element secured by one portion thereof to the member with at least one other portion thereof extending freely from said member, an elongated magnetic element secured at one end 'only to the freely extending portion of said ilrst element and forming a gap between its other end and the first element, the association of said elements affording a limited movement between them at the gap, and windings associated with at least 'one of said elements for varying the ilux traversing said elements in response to energization by voice currents to thereby effect relative vibration between said elements, whereby the resultant reactive vibration of the member is conducted through the connected bone structure to the inner ear ofthe user.

13. In portable bone audition apparatus, the combination of a vibratory member adapted to be operatively connected with the bone structure of the user, and electromagnetic means supported thereby including an elongated magnetically permeable element secured to the member, an elongated magnetic element mounted only at one end on the other element, with its free end forming a gap with said other element, one of said elements being substantially U-shaped and the association of said elements affording a. limited movement between them at the gap, and Windings magnetically associated with at least one of said elements for varying the ilux traversing said elements in response to energization by voice currentsy to thereby effect relative vibration between said elements, whereby the resultant reactive vibration of the member is conducted through the connectedbonestructuretothelnnerearolthe user.

14. In a portable bone audition apparatus, the combination of a vibratory member adapted to be operatively connected with the bone structure of the user, and electromagnetic means supported thereby including an elongated magnetically permeable element secured to the member, an elongated magnetic element mounted only at one end on the other element with its free end form ing a gap with said other element,` at least one oil sald elements being substantially haben@ 0W einem@ the associanonof sam elemente moraine a nmited movement between them at the gap, and

tion between said elements, wereby the resultant reactive vibration of the member is conducted through the connected bone structure to the inner ear of the meer;

' mi( KUCH. 

